Laser Doppler Vibrometry Study of Tympanic Membrane Motion after Myringoplasty with Air-Bone Gap of Unknown Origin

ZHANG Ying; WANG Jie; LI Yongxin

doi:10.3969/j.issn.1672-2922.2016.03.004

Abstract：Objective To study the motion characteristics of tympanic membrane (TM) after myringoplasty with air-bone gap of unknown origin using laser Doppler vibrometry. Methods Between January 2013 and January 2015, 11 pa-tients (11 ears), who presented with conductive hearing loss with no obvious clinical reasons after undergoing myringoplasy, were enrolled in this study. Based on the air-bone conduction gap (ABG) at one year after myringoplasty, the patients were divided into Group A (ABG≤20 dB, 6 ears) and Group B (ABG>20 dB, 5 ears). Thirty young people with normal hearing and normal TM served as the control. Magnitudes of TM vibration at the umbo were measured using laser Doppler vibrome-try (LDV). The relationship between TM vibration magnitudes and ABG were analyzed. Results TM vibration magnitude curves in patients in Group A were similar to the normal control subjects, except for Patients No. 6 and 2. TM Vibration magnitude in Patient 6 was significantly lower than in normal controls, especially at 1000 Hz. Otoscopy showed thickened TM with calcification patches. Audiometry showed essentially no change in ABG before and after the myringoplasty sur-gery. TM vibration magnitude was higher than normal controls in Patient 2, peaking at 1000 Hz. TM was intact with signs of atrophy. ABG was reduced following the myringoplasty surgery. TM vibration magnitude was lower than normal controls in most patients in Group B, except for Patient No. 5, whose TM vibration magnitude was slightly greater than normal con-trols. TM was thin in Patient 5 and ABG was reduced after the myringoplasty surgery. Conclusion After myringoplasty, TM vibration magnitude seems to be correlated with post-operative ABG. TM vibration parallel to normal indicates the probabil-ity of improved ABG.